As with all the international festivals at Yoyogi, there will be performances on the main stage, and food and drinks at the stalls around the plaza. You can see the performance schedule on the official website. The event is 11:00-19:00 on both days.
Event details are taken from official sources whenever possible. It is always prudent to check the official event website before attending to make sure that there have not been any changes. If you know of an error in the calendar, then please let me know through the contact form.